Yep Its DeadPool baby. Basically Wade Wilson/Deadpool was a member of the Weapon X Programme while Wilson previously served as a soldier under the wars till he contracted a terminal cancer. Refusing to die he volunteered himself for the Weapon X programme so that they could pump the healing factor ( from Wolverine's DNA ) into him. Though the healing factor did suppress the cancer cell, Wilson was thoroughly disfigured due to the unstableness of the DNA. It affected his brain and caused him to have several mental disorders including multiple personalities and a penchant for humour.
However, Wade did gain several mutant abilities. Most notable was of course "Super-Agility" and "Super-Strength". While not as powerful as Sabretooth or Wolverine, Wade was extraordinarily strong. Other abilities included proficiency with high-tech weapons and blades. This accounts for his two main weapons : Dual pistols and Dual Katana-Blades. He was also also a proficient martial-artist, comparable to Iron Fist.
When Wilson left the Weapon X Team ( Sabretooth/Wolverine/Maverick eg. ), he served as a mercenary with many criminal organizations. Thats where he adopted the name Deadpool. Of course what was most characteristic was his humour. He liked to break the 4th wall ( indicating he was a comic book character all the time) and had a boyish/perverted sense of humour.
And thus he was nicknamed , " The Merc with a Mouth " ;D